Pneumatic hammer.



No. 655,902. Patented Aug. l4, I900.

c. H. mansion.

PNEUMATIC HAMMER.

(Applichtion filed'flim. a1, 1900.

(No Model.)

;L/M da j TATES PATENT Critics.

CHARLES HARRIS JOHNSON, OF CHICAGO HEIGHTS, ILLINOIS, ASSIGNOR TO THE JOHNSON, PARFITT TOOL COMPANY, OF SPRINGFIELD, ILLINOIS.

PNEUMATIC HAMMER.

SPECIFICATION forming part of Letters ratent No. 655,902, dated August 14, 1900. Application filed Jami- 31,1906. Serial No. 3,606., (No model.)

To all whom it may concern.-

Be it known that 1, CHARLES HARRIS JOHN- SON, a citizen of the United States, residing at Chicago Heights, in the county of Cook, State of Illinois, have inventedcertain new and useful Improvements in Pneumatic Hammers and Like Tools Operated by Fluid-Pressure; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, in which Figure 1 is a longitudinal central section of a pneumatic tool embodying my invention. Fig. 2 is a longitudinal central section of the cylinder, the piston, 00., removed. Fig. 3 is an end view of the tool looking in the direction of the arrow, Fig. 2. Fig. 4 is an end and Fig. 5 a sectional view of the' piston. Fig. 6 is a sectional view, and Fig. 7 an end View, of the annular end plug of the cylinder. Fig. 8 is'an end view, and Fig. 9 a side elevation, of the movable block or button which is struck by the piston or hammer and delivers the blow to the tool proper. Fig. 10 is a sectional View, and Fig. 11 is an end view, of the ferrule or bushing of the plug and which holds the tool proper.

'Like symbols refer to like parts wherever they occur.

My invention relates generally to that class of motive-fluid-operated tools wherein are combined a cylinder and piston, the latter constituting the hammer which delivers the blow either mediately or immediately to the special tool carried by or inserted in the cylinder or case wherein the piston or hammer reciprocates, and especially to that class commonly termed valveless, wherein a differential piston or a piston of different area on opposite ends is employed, and has for its object to eliminate from the construction ports or passages within the walls of the cylinder, whereby a greatly-simplified and thoroughlyeftective tool is obtained.

To this end the main feature of my invention, generally stated, embraces the combination, with asuitable cylinder having an annular groove or channel on its interior and an exhaust-port, of a differential piston hav- ;ing non-communicating passages leading from its opposite ends and which communicate with each other through the annular grooveor channel on the interior of the cylinder, said cylinder having a motive-fluid supply port arranged to maintain a constant pressure on that head of the piston having the lesser area, whereby the reciprocation of the piston is effected.

There are other minor features of invention, all as will hereinafter more fully appear.

I will now proceed to describe my invention more fully, so that others skilled. in the art to which it appertains may apply the same.

1 indicates the tool case or cylinder, formed 011 its interior with the two bores 2 and 3 of different diameters, with the lesser of which,

I 2, the induction-port 4 for the admission of the motive fluid communicates, so thata constant pressure is maintained on the pistonhead of lesser areaduring the operation of the devices.

At some suitable-point in the motive-fluidinduction passage or pipe a suitable throttlevalve T is located. In the present instance one of a particular constructionviz., a plug or piston of different diameters-has been chosen for illustration; but the same is not herein further described, as it forms no part of the present application, being reserved for the subject-matter of a separate application, and it is to be understood that any suitable throttle-valve which will control the induction-passage of the tool may be substituted for the one shown in the drawings.

At or adjacent to the point where the two bores 2 and 3 of the cylinder unite and communicating with the chamber 3 or bore of greatest diameter is formed an air-port 5, which not only admits atmospheric air back of the shoulder of the differential piston, but also provides for the escape of any leakage from the opposite end of the piston.

6 indicates an annular groove or channel formed on the interior of the cylinder about midway of the length of its greater bore 3, of such width as will insure the simultaneous communication therewith of both of the ports or passages of the piston at or about the time the piston has completed its working stroke, (or blow,) and adjacent thereto toward the end of said bore 3 is a second narrower annular groove or channel 7 provided with the exhaust-port 8, extending through the case or cylinder 1.

The tool end of the cylinder is preferably threaded on its interior and closed by means of an annular plug 9, contracted at its inner end by an annular inwardly-proj ectin g shoulder 9, in which is inserted a movable block or button 10, which receives the impact of the piston, and within said annular plug 9., which closes the end of the cylinder 1, is inserted a bushing or ferrule 11, which not only confines and limits the movement of the block or button 10 when struck by the piston, but also serves to hold the rivet-set or tool proper, which is in service.

In order to secure the annular end plug 9 against rotation, it is provided withaspringpressed dog or latch 12, which engages a notch in the end of cylinder 1, the dog or latch being limited in its outward movement by a pin 12 or equivalent means.

The block orbutton 10 is movably fitted within the annular flange or shoulder 9 of end plug 9, so as to transmit the blow of the piston to the tool proper; but the fit is sulficiently tight to prevent any appreciable escape of air from the cylinder 3 below the piston for a short period or until the piston in its return movement has unclosed the eX- haust-port 8 of the cylinder.

13 indicates the differential piston (or hammer)that is to say, a piston corresponding in its respective diameters to the bores 2 and 3 of the cylinder 1, its opposite heads being of different area. That head of the piston toward the induction-port 4 is provided with a passage 14:, which preferably extends inwardly substantially half the length of the piston and connects with a transverse port or passagel t which opens on the periphery of the pistomwhile the opposite (or operative) head of the piston is provided with a similar passage 15 which extends inwardly preferably less than half the length of the piston and opens into a transverse passage 15, which also opens on the periphery of the piston, the two transverse ports let and 15 being in adjacent planes or so arranged that they shall both connect with the annular groove 6 of the cylinder 1 when the piston has completed its operative (blow) stroke. As the port or passage 15 opens on the operative face of piston 13 it is preferably eccentrically placed, while, if desired,.the passage 14E may be located in the axial line of the piston.

The construction of the devices being substantially such as hereinbefore pointed out will operate as follows: The throttle-valve T being operated to admit the fluid-pressure to the cylinder through ind notion-port 4,the pressure will act upon that end of the piston 13 (to the right of the drawings)-having the lesser area, imparting to the piston its working movement, the piston being moved in one direction (to the left in the drawings) until it strikes the block or button 10 and imparts the blow to the tool proper held in the bushing or ferrule 11. By the time the piston has completed its stroke in the given direction (to the left in the drawings) the transverse ports or passages 14 and 15 are in register with the annular groove or channel 6, the piston in the meantime having passed over annular groove or channel 7 and closed the exhaust-port S. The motive fluid passes by passages 14: 14:, channel 6, and passages 15 15 to the opposite end of the cylinder, where,

' acting on that head of the piston having the greatest area, a reverse or return movement is imparted to the piston, which ultimately carries the piston-passages 14 15 out of register with the channel 6 and simultaneously opens exhaust-port 8, whereupon the pressure on the opposite or smaller end of the piston repeats the working stroke thereof. The several steps above noted are successively repeated until such time as the throttle-valve is moved to cut off the flow of motive fluid to the cylinder through the induction-port 4 and put the tool out of action.

Having thus described my invention, what I claim, and desire to secure by Letters Pat ent, is-

1. In a motive-fiuid-operated tool, the combination with a suitable cylinder provided with an exhaust-port of a differential piston having separate ports or passages leading from its opposite ends to its periphery at adjacent points, said cylinder having a supply port arranged to maintain constant pressure on that head of the piston having the lesser area, substantially as andfor the purposes specified.

2. In a motive-fiuid-operated tool, the'combination with a cylinder having a differential bore, an exhaust-port, a motive-fluid-supply port, and an annular groove on its interior at its greatest diameter, of a differential piston having ports or passages leading from its opposite ends to its periphery in adjacent planes and adapted to simultaneously register with the annular groove of the cylinder, substantially as and for the purposes specified.

3. In a motive-fluid-operated tool, the combination with a cylinder having a differential bore provided with an annular groove at its greatest interior diameter, an exhaust groove and port adjacent thereto, and a motive-fluidsupply port, of a differential piston having ports or passages leading from its opposite ends to points on its periphery, the motivefluid-supply port being arranged to maintain constant pressure on that head of the piston having the lesser area, substantially as and for the purposes specified.

4:. In a motive-fiuid-operated tool, the combination With a piston and its cylinder, of an in presence of two Witnesses, this 27th day of annular end plug having an annular flange January, 1900. or shoulder on its interior a ferrule or busha ing, anda block or button interposed between CHARLES HARRIS JOHNSON 5 the piston and ferrule or bushing, substan- W'itnesseszl tially as and for the purposes specified. H. H. VAUGHAN,

In testimony whereof latfix my signature, GEORGE I. MGELDOWNEY. 

